Patent EA-001136-B1 (EA)
Title: Process for obtaining olefins from residual and other recycled products
Inventor: SERRAND WILLIBALD
IPC: C10G11/18
Filed: 1997-02-21
Abstract: 1. A process for producing olefins from a residual feedstock, which process comprises converting the feedstock in a process unit comprised of: (i) a heating zone wherein heat transfer solids containing carbonaceous deposits thereon are received from a stripping zone and heated in the presence of an oxidizing gas; (ii) a vapor short contact time reaction zone containing a bed of fluidized solids comprised of heat transfer solids recycled from the heating zone; and (iii) a stripping zone through which solids having carbonaceous deposits thereon are passed from the reaction zone and wherein lower boiling additional hydrocarbons and volatiles are recovered with a stripping gas; which process comprises: (a) feeding the residual feedstock to said vapor short contact time reaction zone wherein it contacts the fluidized heat transfer solids and catalytic component, which reaction zone is operated at a temperature from about 670 degree C to about 870 degree C and under conditions such that the solids residence time and the vapor residence time are independently controlled, which vapor residence time is less than about 2 seconds and which solids residence time is from about 5 to about 60 seconds, thereby resulting in a material being deposited onto said solids, and a vaporized fraction containing olefinic products, which material is characterized as a combustible carbonaceous metal-containing material; (b) separating the vaporized fraction from the solids; (c) quenching said vaporized fraction to a temperature low enough to stop the conversion; (d) passing the separated solids to said stripping zone where they are contacted with a stripping gas, thereby removing any remaining volatile material therefrom; (e) passing the stripped solids to said heating zone where they are heated to an effective temperature that will maintain the operating temperature of the reaction zone; and (f) recycling heated solids from the heating zone to the reaction zone where they provide the heat of reaction and are contacted with fresh feedstock. 2. A process according to claim 1 which further comprises coverting a hydrocarbon feedstock having an average boiling point from about the C5 hydrocarbon boiling point to about 545 degree C to lower boiling products by: (i) introducing said feedstock into a steam cracking furnace wherein said feedstock is vaporized and cracked to lower boiling products in the presence of steam; (ii) quenching said vaporized and cracked product stream to a temperature low enough to stop the cracking reaction; and (iii) combining said quenched vapor stream with the quenched vapor stream from step (c) according to claim 1 in a common downstream steam cracking facility selected from the group consisting of fractionation, compression, scrubbing of contaminants, and olefins recovery. 3. A process according to any of the preceeding claims which further comprises separating an olefin-rich fraction from the quenched vaporized fraction from step (c). 4. A process according to any of the preceeding claims wherein the vapor short contact time reaction zone contains a horizontal moving bed of fluidized solids. 5. A process according to any of the preceding claims wherein the solids of the vapor short contact time reaction zone are fluidized with the aid of a mechanical means and a fluidizing gas. 6. A process according to any of the preceding claims wherein the mechanical means are comprised of a set of horizontally disposed screws within the reactor. 7. A process according to any of the preceding claims wherein the heat transfer solids are selected from the group consisting of petroleum coke from a delayed coking process, recycle coke, or an inert material such as sand. 8. A process according to any of the preceding claims wherein the heat transfer solids have a catalytic component. 9. A process according to any of the preceding claims wherein the catalytic component is metal oxides selected from the group consisting of magnesium oxide, calcium oxide, manganese oxide, beryllium oxide, strontium oxide, cerium oxide, vanadium oxide, cesium oxide, and mixtures thereof. 10. A process according to any of the preceding claims wherein the catalytic component is selected from the group consisting of refractory metal oxides, aluminates, zeolites, spent fluid catalytic cracking catalysts, vanadium rich flue fines, spent bauxite, and mixtures thereof. 11. A process according to any of the preceding claims wherein the vapor residence time of the vapor short contact time reaction zone is less than about 1 second. 12. A process according to claims 1 through 10 wherein the vapor residence time is less than about 0.5 seconds. 13. A process according to claims 1 through 10 is less than about 0.25 seconds. 14. A process according to any of the preceding claims wherein the solids residence time of the vapor short contact time reaction zone is from about 10 to 30 seconds. 15. A process according to any of the preceding claims wherein the residual feedstock is selected from the group consisting of vacuum resids, atmospheric resids, heavy and reduced petroleum crude oil, pitch, asphalt, bitumen, tar sand oil, shale oil, coal slurries and coal liquefaction bottoms. 16. A process according to claims 1 through 14 wherein the residual feedstock is a vacuum resid. 17. A process according to any of the preceding claims wherein a co-feed selected from the group consisting of a lube extract stream, a deasphalted rock petrolatum, and heavy products from fluidized catalytic cracking, fluidized coking, and delayed coking boiling in excess of 260 degree C is added to the residual feedstock. 18. A process according to any of the preceding claims wherein less than 50 wt.% of the feedstock is said co-feed. 19. A process according to any of the preceding claims wherein the stripping gas is steam. 20. A process according to any of the preceding claims wherein the fluidizing gas is comprised of normally gaseous hydrocarbons, hydrogen, hydrogen sulfide, and added steam. 21. The process according to any of the preceding claims which reaction zone is operated at a temperature from about 760 degree C to about 790 degree C. 22. The process according to any of the preceding claims wherein steam is added to the residual feedstock at a rate from about 0.2 to 0.5 kg per kg. of residual feedstock plus co-feed. 23. A process according to any of the preceding claims wherein the fluidizing gas is comprised of vaporized normally gaseous hydrocarbons, hydrogen, hydrogen sulfide, and steam.